A transition metal bearing precursor material and a method for preparing the same

Abstract

This invention relates to a S-free and Cl-free transition metal bearing precursor material, its use for preparing a positive electrode active material; to a positive electrode active material for rechargeable batteries, to a method for preparing this transition metal bearing precursor material and a method for preparing the positive electrode active material; and to a battery comprising said positive electrode active material.

Description

[0001] A TRANSITION METAL BEARING PRECURSOR MATERIAL AND A METHOD FOR PREPARING THE SAME

[0002] TECHNICAL FIELD OF THE INVENTION

[0003] This invention relates to a S-free and Cl-free transition metal bearing precursor material, its use for preparing a positive electrode active material; to a positive electrode active material for rechargeable batteries, to a method for preparing this transition metal bearing precursor material and a method for preparing the positive electrode active material; and to a battery comprising said positive electrode active material.

[0004] BACKGROUND OF THE INVENTION

[0005] Energy storage systems such as rechargeable batteries are necessary for quickly storing and releasing high amounts of energy to adjust power output to demand. The same battery technology goes into electric vehicles, which run on stored electrical energy and reduce pollution compared to conventional vehicles with internal combustion engines. To meet proper demands, these batteries need to store high levels of energy with minimal weight, charge and discharge at fast rates, and go through many cycles without diminishing in performance. These demands are respectively referred to as high energy density, rate capability, and cyclability, and must be reached while batteries remain affordable and safe. Particularly because of their high energy density and rate capability, many kinds of lithium-ion batteries (LIBs) are widely studied to meet these needs.

[0006] CN113363493A provides a single-crystal ternary positive electrode active material and a preparation method thereof starting from a step of mixing a transition metal precursor and a lithium source. The transition metal precursors are prepared by using transition metal sulfate solutions, transition metal chloride solutions, transition metal nitrate solutions, or their combinations. The transition metal precursors either contain Cl or S or have a relatively lower Ni content (i.e. 70 mol% of Ni relative to the sum of Ni, Mn, and Co). The cost of the method proposed by CN113363493A is high because of its long process time.

[0007] CN109811412B provides a layered lithium nickel manganate positive electrode active material with a single-crystal morphology and a preparation method thereof with the aim to eliminate the scarce resource Co and greatly reduce material preparation costs It discloses a transition metal precursor having a Ni to Mn ratio of 50 mol% to 50 mol% which is prepared by using transition metal nitrate solution or a combination of transition metal nitrate and sulfate solutions. The method however uses a presintering step and calcination step which increases the process time and cost.

[0008] These abovementioned prior art discloses methods for producing single-crystal (monolithic) positive electrode active materials, which use a relatively high sintering (heating) temperature and a relatively long sintering time.

[0009] It is an object of the present invention to provide a transition metal bearing precursor which enables the use of a lower sintering temperature or a shorter sintering time, resulting in a decreased process cost.

[0010] It is a further object of the present invention to provide a method for preparing said precursor material, which does not inhibit the growth process of the particles during heating.

[0011] It is a further object of the present invention to provide a method for preparing a positive electrode active material, which uses a shorter processing time and lower sintering temperature so that the process has good economic effect.

[0012] SUMMARY OF THE INVENTION

[0013] A positive electrode active material with monolithic morphology (referred to monolithic material) is preferred in some battery applications due to the relatively better hardness and lower specific surface area in comparison with a positive electrode active material with polycrystalline morphology (referred to polycrystalline material). The better hardness prevents formation of microcracks during processing and lower specific surface area reduces side reactions between the positive electrode active material and electrolytes. However, the synthesis of the monolithic material requires a high sintering temperature and long sintering time to fuse all primary particle into single particles. The use of precursor with low or no sulfur content is expected to ease the growth of the monolithic particle since sulfur behaves as sintering inhibitor. A precursor prepared from metal nitrate sources could be used. In a first aspect, the object of the present invention is achieved by providing a transition metal bearing precursor material for positive electrode active material for rechargeable batteries, comprising M' and oxygen, wherein M' comprises:

[0014] Ni in a content x, wherein 70.0 < x < 100.0 at%, relative to M',

[0015] Mn in a content y, wherein 0.0 < y < 30.0 at%, relative to M',

[0016] Co in a content z, wherein 0.0 < z < 25.0 at%, relative to M',

[0017] D in a content b, wherein 0.0 < b < 2.0 at%, relative to M', wherein D is at least one element selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, Sr, Ti, V, W, Y, Zn, and Zr; characterized in that M' further comprises S in a content a, wherein a is 0.0 < a < 0.005 at% and Cl in a content c, wherein c is 0.0 < c < 0.005 at%, relative to M'; and wherein x, y, z, a, b and c are measured by ICP-OES; and x+y+z+a+b+c is 100.0 at%.

[0018] In a further object, the present invention discloses the use of said transition metal bearing precursor material for preparing a positive electrode active material.

[0019] In a further object, the present invention discloses a positive electrode active material obtained by using said transition metal bearing precursor material, wherein said positive electrode active material comprises monolithic particles. The inventors provided a positive electrode active material which achieved a narrower span.

[0020] In a further object, the present invention provides a method for preparing said precursor material through a nitrate based precipitation.

[0021] In a further object, the present invention provides a method for preparing a positive electrode active material. Both methods reduce the production costs in using lower sintering temperature or sintering time.

[0022] In a further object, the present invention provides a battery comprising said positive electrode active material. BRIEF DESCRIPTION OF THE FIGURES

[0023] Further features and advantages of the invention can be ascertained from the following detailed description that is provided in connection with the Figure described below:

[0024] Figure 1 : SEM image of precursor B

[0025] Figure 2: SEM image of EXI

[0026] DETAILED DESCRIPTION

[0027] In the following detailed description, preferred embodiments are described in detail to enable practice of the invention. Although the invention is described with reference to these specific preferred embodiments, it will be understood that the invention is not limited to these preferred embodiments. To the contrary, the invention includes numerous alternatives, modifications and equivalents as will become apparent from consideration of the following detailed description and accompanying figures.

[0028] The term "comprising", as used herein and in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It needs to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. Thus, the scope of the expression "a composition comprising components A and B" should not be limited to compositions consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the composition are A and B. Accordingly, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of" and "consisting of".

[0029] The term "a positive electrode active material" (also known as cathode active material or CAM) as used herein and in the claims is defined as a material which is electrochemically active in a positive electrode or cathode. By active material, it must be understood to be a material capable to capture and release Li ions when subjected to a voltage change over a predetermined period of time.

[0030] In the framework of the present invention, at% signifies atomic percentage. The at% or "atomic percent" of a given element expression of a concentration means how many percent of all atoms in the concerned compound are atoms of said element. The designation at% is equivalent to mol% or "molar percent".

[0031] The term "median particle size D50" (also known as median particle size by volume Dv50), as defined herein, can be interchangeably used with the terms "D50" or "d50" or "median particle size" or "a median particle size (d50 or D50)". D50 is defined herein as the particle size at 50% of the cumulative volume% distributions. D50 is typically determined by laser diffraction particle size analysis. DIO and D90 (DvlO and Dv90) are defined as particle sizes at 10% and 90% of cumulative volume% distribution when measured by laser scattering method as described in this specification, respectively. The term "span", as used in the text, is defined as (D90 - D10) divided by D50; i.e. (D90-D10) / D50. The term "narrow span" stands for a span of 1.0 or less than 1.0.

[0032] The term "monolithic", as defined herein, signifies in certain preferred embodiments of the present invention, that the positive electrode active material is a powder comprising monolithic particles, which consists of single particles and / or secondary particles, wherein each of the single particles consists of only one primary particle and each of the secondary particles consists of at least two primary particles and at most twenty primary particles as observed in a SEM image.

[0033] A transition metal bearing precursor

[0034] In a first aspect, the present invention provides a transition metal bearing precursor material for positive electrode active material for rechargeable batteries, comprising M' and oxygen, wherein M' comprises:

[0035] Ni in a content x, wherein 70.0 < x < 100.0 at%, relative to M', Mn in a content y, wherein 0.0 < y < 30.0 at%, relative to M', Co in a content z, wherein 0.0 < z < 25.0 at%, relative to M', D in a content b, wherein 0.0 < b < 2.0 at%, relative to M', wherein D is at least one element selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, Sr, Ti, V, W, Y, Zn, and Zr; characterized in that M' further comprises S in a content a, wherein a is 0.0 < a < 0.005 at% and Cl in a content c, wherein c is 0.0 < c < 0.005 at%, relative to M'; and wherein x, y, z, a, b and c are measured by ICP-OES; and x+y+z+a+b+c is 100.0 at%. In a preferred embodiment of the transition metal bearing precursor material, x is 80.0 < x < 95.0 at%. In another preferred embodiment of the transition metal bearing precursor material y is 1.0 < y < 10.0 at%. In a further preferred embodiment of the transition metal bearing precursor material z is 1.0 < z < 10.0 at%. In another further embodiment of the transition metal bearing precursor material a is a < 0.001 at%.

[0036] In another embodiment, the transition metal bearing precursor material has a median particle size D50 of between 1 pm and 10 pm, preferably between 2 pm and 8 pm, as determined by laser diffraction particle size analysis.

[0037] The transition metal bearing precursor material usually is in a powder form.

[0038] Positive electrode active material

[0039] In a second aspect, the present invention discloses the use of said transition metal bearing precursor material for preparing a positive electrode active material.

[0040] In a further aspect, the present invention discloses a positive electrode active material obtained by using the transition metal bearing precursor material according to the first aspect of invention, wherein the positive electrode active material has a median particle size D50 of between 1 pm and 10 pm, as determined by laser diffraction particle size analysis. In a more preferred embodiment of the positive electrode active material the D50 is between 2 pm and 8 pm, most preferably between 2 pm and 4 pm.

[0041] In a preferred embodiment the positive electrode active material comprises monolithic particles. In a more preferred embodiment the monolithic particles are spherical. In an even more preferred embodiment, the monolithic particles have an average circularity of more than 0.85.

[0042] In another preferred embodiment the positive electrode active material has a span of less than 1.0; i.e. the inventors provided a positive electrode active material which achieved a narrower span. The narrow span of a positive electrode active material results in better safety and cycle stability caused by homogeneous distribution of the positive electrode active material in a positive electrode. In addition, the narrow span results in potentially higher energy density of a battery because it allows to design a battery electrode having a higher volumetric packing density.

[0043] Method for preparing a transition metal bearing precursor

[0044] In a third aspect, the present invention provides a method for preparing a transition metal bearing precursor wherein said precursor is prepared by a co-precipitation process using transition metal salt source, sodium hydroxide, and ammonia, wherein the transition metal salt source is a nitrate salt source comprising Ni(NO3)2, Mn(NO3)2 and CO(NO3)2.

[0045] The inventors found that monolithic particles having a preferable D50 can be obtained with a lower sintering temperature and a shorter sintering time when a precursor which does not contain S or Cl is used because S and Cl inhibit the growth of a particle.

[0046] The method for preparing a transition metal bearing precursor according to the invention comprises: supplying a flow of a transition metal salt solution comprising the one or more transition metal elements but not comprising S and Cl to a reactor vessel for a time period, during the time period, mixing the transition metal salt solution with an aqueous solution comprising one or more alkali hydroxides and an aqueous solution of ammonia (NH3(aq)), thereby precipitating a hydroxide of the one or more transition metal elements and forming the aqueous slurry comprising hydroxide or oxyhydroxide particles of the one or more transition metal elements, wherein during the time period, maintaining in the reactor vessel: a range of pH value of the aqueous slurry, the range being superior or equal to 10.5 and inferior or equal to 12.5, preferably superior or equal to 11.0 and inferior or equal to 12.0, wherein the pH value of the aqueous slurry is the pH value as measured on a sample of the aqueous slurry after cooling to 20 °C, a concentration of NH3(aq) of superior or equal to 1 g / L and preferably inferior or equal to 3 g / L, and a temperature of the aqueous slurry which is at least 70 °C and at most 99 °C, preferably at least 80 °C and at most 90 °C; wherein after the end of the time period the aqueous slurry in the reactor vessel is further processed by separating a solid fraction from a liquid fraction and drying the solid fraction to obtain the transition metal bearing precursor.

[0047] Method for preparing a positive electrode active material

[0048] In a fourth aspect, the present invention provides a method for preparing the positive electrode material according to the second aspect of present invention, wherein the method comprises the following steps:

[0049] 1) preparing a transition metal bearing precursor,

[0050] 2) mixing said transition metal bearing precursor with Li source so as to prepare a mixture,

[0051] 3) heating the mixture so as to prepare a heated product,

[0052] 4) milling the heated product so as to prepare a milled product, and

[0053] 5) optionally drying the milled product so as to prepare a positive electrode active material.

[0054] In one preferred embodiment of this method the milling in the step 4) is performed by a wet milling process such as wet bead (ball) milling and wet ultrasonication. As alternative milling techniques the method can use a dry milling such as air jet milling, and air classifying milling.

[0055] In a preferred embodiment, the method comprises the following steps:

[0056] 1) preparing a transition metal bearing precursor,

[0057] 2) mixing said transition metal bearing precursor according to the first aspect of the invention, a lithium source, and optionally dopant source to obtain a mixture,

[0058] 3) heating the mixture in oxidizing atmosphere at a heating temperature between 750 °C to 1000 °C to obtain a heated product,

[0059] 4) milling the heated product to obtain a milled product, preferably in an aqueous solution, more preferably in water using ultrasonication method,

[0060] 5) drying the milled product at a drying temperature between 30 °C to 200 °C, preferably in vacuum, to obtain the positive electrode active material.

[0061] In an embodiment of the fourth aspect of the present invention, step 1) is performed according to the method of the third aspect of the present invention in any of its embodiments or combination of embodiments. Battery

[0062] In a further aspect, the present invention provides a battery comprising the positive electrode active material as described above according to the second aspect of the invention.

[0063] In a preferred embodiment the battery is a lithium-ion battery, preferably a lithium- ion rechargeable battery. Preferably the battery comprises a positive electrode comprising the cathode active material according to the first aspect of the invention, a negative electrode, an electrode, and a separator.

[0064] In additional aspect the present invention concerns a use of the battery according to the last aspect of the invention in either one of a portable computer, a tablet, a mobile phone, an energy storage system (ESS), an electric vehicle (EV) or in a hybrid electric vehicle (HEV), preferably in an electric vehicle or in a hybrid electric vehicle.

[0065] EXAMPLES and EXPERIMENTAL TESTS

[0066] The invention will be described below in greater detail with reference to examples, but the invention is not limited in any way by these examples, as long as it does not exceed the scope and spirit of the present invention.

[0067] Experimental tests used in the examples

[0068] The following analysis methods are used in the Examples:

[0069] A) Particle size distribution (PSD) analysis

[0070] The PSD is measured using a Malvern Mastersizer 3000 with Hydro MV wet dispersion accessory after dispersing examples as described herein below of positive electrode active material powders in an aqueous medium. To improve the dispersion of the positive electrode active material powder examples, sufficient ultrasonic irradiation and stirring is applied, and an appropriate surfactant is introduced. D10, D50, and D90 are defined as the particle size at 10%, 50%, and 90% of the cumulative volume% distributions, respectively. Span is defined as (D90-D10) / D50.

[0071] B) Inductively coupled plasma - optical emission analysis (ICP-OES) analysis

[0072] The positive electrode active material examples as described herein below are measured by the Inductively Coupled Plasma - Optical Emission Spectrometry (ICP- OES) method using an Agillent ICP 720-OES. 1 gram of a powder sample of each example is dissolved into 50 mL high purity hydrochloric acid in an Erlenmeyer flask. The flask is covered by a watch glass and heated on a hot plate at 380°C until complete dissolution of the sample. After being cooled to room temperature, the solution and the rinsing water of Erlenmeyer flask are transferred to a 250 mL volumetric flask. Afterwards, the volumetric flask is filled with DI water up to the 250 mL mark, followed by complete homogenization. An appropriate amount of solution is taken out by pipette and transferred into a 250 mL volumetric flask for the 2nddilution, where the volumetric flask is filled with internal standard and 10% hydrochloric acid up to the 250 mL mark and then homogenized. Finally, this solution is used for ICP-OES measurement. The elemental contents are expressed as at% of the total of these contents.

[0073] C) Scanning Electron Microscope

[0074] The morphology of positive electrode active materials is analyzed by a Scanning Electron Microscopy (SEM) technique. The measurement is performed with a JEOL JCM-6100 Plus under a high vacuum environment of 9.6xl0'5Pa at 25°C. The particles in the image should be well distributed therefore avoiding overlap between particles. This can be achieved by pouring a small amount of powder sample to the adhesive attached on the SEM sample holder and blowing air to remove the excess powder.

[0075] EXAMPLES

[0076] The present invention is further illustrated in the following examples:

[0077] Comparative Example 1 to comparative example 8

[0078] Comparative Example 1 (CEX1) provides a positive electrode active material having a monolithic morphology, which was prepared according to the following steps:

[0079] 1) Precursor A preparation: a transition metal-based precursor (precursor A) with metal ratio Ni: Mn:Co of 0.88:0.05:0.07 was prepared by a co-precipitation process in a large-scale continuous stirred tank reactor (CSTR.) with mixed nickel- manganese-cobalt sulfates, sodium hydroxide, and ammonia. The precursor A of rough composition Nio.ssMno.osCoo.o? (OH)2 further comprises around 0.01 mol% of S and 0.0 mol% of Cl, relative to the sum of Ni, Mn, and Co. The precursor A has a median particle size D50 of 3.3 pm, DIO of 2.2 pm, D90 of 5.0 pm, and span of 0.86.

[0080] 2) Mixing: the precursor A prepared from Step 1) was homogenously mixed to obtain a mixture with a lithium to metal (Ni, Mn, and Co) ratio of 0.96.

[0081] 3) Heating: the mixture from Step 2) was heated at 820 °C for 2.5 hours under an oxygen atmosphere to obtain a heated powder.

[0082] 4) Milling: The heated powder from Step 3) was milled by a wet ultrasonication method using an ultrasonic probe. 20 grams of the heated powder was added into 150 grams of water in a 400 mL cylinder container having inner diameter of 82 mm. Ultrasonic was applied for 60 minutes with a power of 1500 watt to obtain a milled powder.

[0083] 5) Drying: The milled powder from Step 4) was collected by filtration followed by drying in vacuum at 50°C for 12 hours to obtain CEX1.

[0084] CEX2 to CEX8 were prepared according to the same method as CEX1, except that the heating temperature and time is according to Table 1.

[0085] For the comparative examples' co-precipitation process NiSO4-6H2O was used as the nickel raw material, CoSO4-7H2O as the cobalt raw material, and MnSO4-H2O as the manganese raw material. These raw materials were dissolved in distilled water to prepare a metal salt aqueous solution. After preparing the co-precipitation reactor, N2was purged to prevent oxidation of metal ions during the coprecipitation reaction, and the temperature of the reactor was maintained at 40-70°C. NH4(OH) was added to the co-precipitation reaction as a chelating agent, and NaOH was used for pH control. The precipitate obtained by the co-precipitation process was filtered, washed with distilled water, and then dried in a cake dryer at 140-190°C to prepare a comparative positive electrode active material precursor A.

[0086] Example 1 to example 8

[0087] Example 1 (EXI) provides a positive electrode active material having a monolithic morphology, which was prepared according to the following steps:

[0088] 1) Precursor B preparation:

[0089] A metal feed solution with metal ratio Ni: Mn:Co of 0.88:0.05:0.07 was prepared by using metal nitrate salts Ni(NO3)-6H2O, Mn(NO3)2-4H2O and Co(NO3)2-6H2O. The total metal content in the metal feed solution was 120 g / L. A precipitation was carried out as a batch precipitation in 10 L reactor. The starting batch consisted of 4500 mL of H2O, 60 ml of ammonia solution and 2 L of Ni(OH)2seed slurry that had D50 of 1.2 pm. Total seed amount in the start batch was 220 grams and ammonia content was 2 g / L. The pH was adjusted with NaOH to 11.5. The reactor was heated to 85 °C and the stirring speed of an agitator in the reactor was 1000 rpm (rotation per a minute).

[0090] The metal feed solution was added to the reactor with a flow rate of 10 mL / min for the first 4 hours. The flow rate steadily increased from 10 mL / min to 56 mb / min so that a calculated growth rate of particles remained around 0.1 pm / hour.

[0091] An ammonia (NH3) solution was added to the reactor and adjusted so that ammonia content in the reactor remained 2-4 g / L. A NaOH solution was added to the reactor and adjusted to keep the pH at 11.5-11.8 (20 °C). The concentration of ammonia in the ammonia solution was 220 g / L and the concentration of NaOH in the NaOH solution was 230 g / L.

[0092] When particle size was at target the precipitation was stopped so as to prepare a precipitated slurry. The total precipitation time was 21 hours.

[0093] The slurry was filtered and mixed with 60 °C water using ratio of 10 L water to 1 L of slurry and dried in 120 °C to obtain precursor B.

[0094] The Precursor B of rough composition Nio.ssMno.osCoo.o? (OH)2further comprises comprises 0.0 mol% of S and 0.0 mol% of Cl, relative to the sum of Ni, Mn, and Co. The precursor B has a median particle size D50 of 3.2 pm, D10 of 2.3 pm, D90 of 4.5 pm, and span of 0.66. ) Mixing: the precursor B prepared from Step 1) were homogenously mixed to obtain a first mixture with a lithium to metal (Ni, Mn, and Co) ratio of 0.96.) Heating : the mixture from Step 2) was heated at 820 °C for 2.5 hours under an oxygen atmosphere to obtain a heated powder. ) Milling : The heated powder from Step 3) was milled by a wet ultrasonication method using an ultrasonic probe. 20 grams of the heated powder was added into 150 grams of water in a 400 mL cylinder container having inner diameter of 82 mm. Ultrasonic was applied for 60 minutes with a power of 1500 watt to obtain a milled powder. ) Drying : The milled powder from Step 4) was collected by filtration followed by drying in vacuum at 50 °C for 12 hours to obtain EXI. EX2 to EX8 are prepared according to the same method as CEX1, except that the heating temperature and time is according to Table 1.

[0095] Precursors A and B have a very similar composition and particle size distribution.

[0096] Further precursor examples were prepared from metals sulfates. A transition metalbased precursor (precursor C) with metal ratio Ni: Mn:Co of 0.93:0.02:0.09 was prepared similarly to precursor A. The precursor C of rough composition Ni0.93Mn0.02Co0.09 (OH)2further comprises around 0.14 mol% of S and 0.0 mol% of Cl, relative to the sum of Ni, Mn, and Co. The precursor C has a median particle size D50 of 3.2 pm, D10 of 2.2 pm, D90 of 4.7 pm, and span of 0.80. A transition metalbased precursor (precursor D) with metal ratio Ni :Mn:Co of 0.82:0.06:0.12 was prepared similarly to precursor A. The precursor D of rough composition Ni0.82Mn0.06Co0.12 (OH)2further comprises around 0.21 mol% of S and 0.0 mol% of Cl, relative to the sum of Ni, Mn, and Co. The precursor D has a median particle size D50 of 10.3 pm, D10 of 5.5 pm, D90 of 18.0 pm, and span of 1.21. A transition metal-based precursor (precursor E) with metal ratio Ni: Mn:Co of 0.68:0.20:0.12 was prepared similarly to precursor A. The precursor E of rough composition Nio.68Mn0.2oCoo.i2 (OH)2further comprises around 0.01 mol% of S and 0.0 mol% of Cl, relative to the sum of Ni, Mn, and Co. The precursor D has a median particle size D50 of 5.0 pm, D10 of 2.9 pm, D90 of 8.1 pm, and span of 1.21.

[0097] As these comparative examples illustrate, independently of the metal ratio Ni : Mn:Co and of the particle size, whenever metal sulfates are precipitated, Sulfur was incorporated in the precursor composition. As is shown herein, such sulfur contents have an impact on the final active material.

[0098] Results

[0099] Table 1. Summary of the heating conditions and particle size of the examples and comparative examples CEX1 to CEX8 are the positive electrode active materials prepared from precursor A comprising around 0.01 mol% of S relative to the sum of Ni, Mn, and Co. On the other hand, EXI to EX8 are the positive electrode active materials prepared from precursor B which is obtained from a precipitation process using nitrate salts and therefore contains no S and no Cl. It can be observed from Table 1 that with the same heating condition, positive electrode active material prepared from precursor B achieved a bigger D50 and narrower span.

[0100] As example, CEX1 prepared by heating for 2.5 hours at 820 °C shows D50 of 1.89 pm and span of 1.13 while EXI prepared by the same heating condition shows D50 of 2.99 pm and span of 0.94. The bigger size of EXI in comparison with CEX1 is associated with the absence of S in the precursor which otherwise will inhibit the growth process during heating.

Claims

CLAIMS1. A transition metal bearing precursor material for positive electrode active material for rechargeable batteries, comprising M' and oxygen, wherein M' comprises:Ni in a content x, wherein 70.0 < x < 100.0 at%, relative to M',Mn in a content y, wherein 0.0 < y < 30.0 at%, relative to M',Co in a content z, wherein 0.0 < z < 25.0 at%, relative to M',D in a content b, wherein 0.0 < b < 2.0 at%, relative to M', wherein D is at least one element selected from the group consisting of Al, B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, Sr, Ti, V, W, Y, Zn, and Zr; characterized in that M' further comprises S in a content a, wherein a is 0.0 < a < 0.005 at% and Cl in a content c, wherein c is 0.0 < c < 0.005 at%, relative to M'; and wherein x, y, z, a, b and c are measured by ICP-OES; and x+y+z+a+b+c is 100.0 at%.

2. The transition metal bearing precursor material according to claim 1, wherein 80.0 < x < 95.0 at%.

3. The transition metal bearing precursor material according to claim 1 or 2 , wherein 1.0 < y < 10.0 at%.

4. The transition metal bearing precursor material according to any of the previous claims, wherein 1.0 < z < 10.0 at%.

5. The transition metal bearing precursor material according to any of the previous claims, wherein a < 0.001 at%.

6. The transition metal bearing precursor material according to any of the previous claims, wherein the transition material bearing precursor has a median particle size D50 of between 1 pm and 10 pm; preferably between 2 pm and 8 pm, as determined by laser diffraction particle size analysis.

7. Use of the transition metal bearing precursor material according to any one of the previous claims for preparing a positive electrode active material.

8. A positive electrode active material obtained by using the transition metal bearing precursor material according to claims 1 to 6, wherein the positive electrode active material has a median particle size D50 of between 1 pm and 10 pm, as determined by laser diffraction particle size analysis.

9. The positive electrode active material according to claim 8, wherein the positive electrode active material has a span of less than 1.0.

10. The positive electrode active material according to claim 8 or 9, wherein the positive electrode active material comprises monolithic particles.

11. A method for preparing a transition metal bearing precursor according to claim 1 to 6, wherein said precursor is prepared by a co-precipitation process using transition metal salt source, sodium hydroxide, and ammonia, wherein the transition metal salt source is a nitrate salt source comprising Ni(NOs)2, Mn(NOs)2 and CoCNCh12. A method for preparing a positive electrode active material according to claim 8 to 10, wherein the method comprises the following steps:1) preparing a transition metal bearing precursor,2) mixing said transition metal bearing precursor with Li source so as to prepare a mixture,3) heating the mixture so as to prepare a heated product,4) milling the heated product so as to prepare a milled product, and5) optionally drying the milled product so as to prepare a positive electrode active material.

13. The method according to claim 12, wherein the milling in the step 4) is performed by a wet milling process.

14. The method according to claim 12 or 13, wherein in step 1) the preparation of a transition metal bearing precursor is prepared by a co-precipitation process using transition metal salt source, sodium hydroxide, and ammonia, wherein the transition metal salt source is a nitrate salt source comprising Ni(NOs)2, Mn(NOs)2 and CoCNCh15. A battery comprising a positive electrode active material according to claim 8 to 10.

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